Methods and devices for estimating the position of an RF source
A sensor system may be configured to identify a location of a radio frequency (RF) source using an angle of arrival estimation technique. A sensor system may identify a candidate location of an RF source using hyperbola positioning techniques with two or more antennas at a similar geolocation with reference to the RF source. The sensor system may additionally be able to identify a plurality of RF sources using two or more antennas at a similar geolocation.
1 . A system for identifying at least one RF source, the system comprising:
one or more hardware processors, the one or more hardware processors configured to:
generate a first set of candidate locations for an RF source based at least in part on a cross correlation of signals received at a first antenna and a second antenna of a sensor system, the first antenna and second antenna being in a first orientation, the first antenna positioned adjacent to the second antenna;
move the first antenna and the second antenna from the first orientation into a second orientation;
generate a second set of candidate locations for the RF source based at least in part on a cross correlation of received signals at the first antenna and the second antenna of the sensor system, the first antenna and second antenna being in the second orientation;
estimate a location of the RF source based on an intersection of the first set of candidate locations and the second set of candidate locations.
2 . The system of claim 1 , wherein the first and second antenna are spaced a distance from each other a multiple of a wavelength of a carrier wave of the RF source.
3 . The system of claim 2 , wherein the distance comprises less than or equal to one wavelength of a carrier wave of the RF source.
4 . The system of claim 3 , wherein the distance comprises up to and including approximately one meter.
5 . The system of claim 1 , wherein to generate the first set of candidate locations, the one or more processors are configured to determine a first set of candidate angles for the RF source based on the cross correlation of signals received at the first and second antennas when the first and second antennas are in the first orientation; and determine the first set of candidate locations based on a projection of the first set of candidate angles on a plane.
6 . The system of claim 1 , wherein the first set of candidate locations includes at least one hyperbolic portion.
7 . The system of claim 1 , wherein to generate the second set of candidate locations, the one or more processors are configured to determine a second set of candidate angles for the RF source based on the cross correlation of signals received at the first and second antennas when the first and second antennas are in the second orientation; and determine the first set of candidate locations based on a projection of the second set of candidate angles on a plane.
8 . The system of claim 1 , wherein the second set of candidate locations includes at least one hyperbolic portion.
9 . The system of claim 1 , wherein the estimated location is in both the first and second sets of candidate locations.
10 . The system of claim 1 , wherein the estimated location is in either the first or second sets of candidate locations.
11 . The system of claim 1 , wherein the one or more hardware processors are configured to estimate the location of the RF source by computing confidence values for candidate locations in the first and second set of candidate locations.
12 . The system of claim 1 , wherein the estimated location corresponds to a highest confidence value.
13 . The system of claim 1 wherein an intersection comprises a density of overlapping location estimates in the first and second candidate locations.
14 . The system of claim 1 wherein an intersection comprises an intersection point in or near an overlapping region of the first and second sets of candidate locations.
15 . The system of claim 1 , wherein moving the first antenna and the second antenna from the first orientation into the second orientation comprises rotating at least one of the first antenna or the second antenna around a point associated with the sensor system.
16 . A system for determining a location of at least one RF source previously unidentified RF source, the system comprising:
a movable platform;
a plurality of antennas coupled to the movable platform,
wherein the plurality of antennas configured to receive signals from a plurality of RF sources in an environment of the movable platform,
wherein at least one pair of antennas of the plurality of antennas are spaced a distance from each other of less than or equal to one wavelength of a carrier wave of the RF source; and
one or more hardware processors configured to communicate with the plurality of antennas and identify a presence of at least one RF source of the plurality of RF sources based at least in part on a received power associated with the signals and two or more cross correlations of signals received at different pairs of antennas of the plurality of antennas.
17 . The system of claim 16 , wherein the movable platform comprises a winged aircraft or drone.
18 . The system of claim 17 wherein the plurality of antennas comprises three antennas.
19 . The system of claim 16 wherein the one or more hardware processors are configured to estimate a location of the at least one RF source of the plurality of RF sources.
20 . The system of claim 16 comprising at least one actuator configured to rotate the plurality of antennas.